This prospective, single-center observational study aims to evaluate the predictive value of the internal jugular vein collapsibility index (IJVCI) for spinal anesthesia-associated hypotension in preeclamptic parturients (gestational age ≥28 weeks) undergoing cesarean delivery classified as Lucas category 3-4. Preoperative IJVCI will be measured using ultrasonography before spinal anesthesia during spontaneous and deep respiration. The incidence of hypotension within the first 20 minutes after spinal anesthesia will be recorded. The diagnostic performance of IJVCI in predicting hypotension will be analyzed.

This prospective, single-center observational study is designed to evaluate the predictive value of the internal jugular vein collapsibility index (IJVCI) for spinal anesthesia-associated hypotension in preeclamptic parturients undergoing cesarean delivery classified as Lucas category 3-4.

Eligible patients aged 18-45 years with ASA physical status II-III and singleton pregnancies at ≥28 weeks of gestation will be enrolled. Preoperative ultrasonographic measurements of the right internal jugular vein will be performed to calculate IJVCI using M-mode imaging. Maximum and minimum diameters during spontaneous and deep respiration will be recorded.

Spinal anesthesia will be performed with hyperbaric bupivacaine. Hemodynamic parameters (systolic, diastolic and mean arterial pressure, heart rate, and oxygen saturation) will be monitored with blood pressure measurements every 2 minutes during the first 20 minutes and then every 5 minutes thereafter. Hypotension will be defined as a ≥30% decrease in mean arterial pressure from baseline or systolic blood pressure <100 mmHg. Hypotension will be treated according to the study protocol with ephedrine boluses as needed.

The primary outcome is the incidence of spinal anesthesia-associated hypotension within the first 20 minutes after spinal anesthesia. Secondary outcomes include total ephedrine consumption, number and duration of hypotensive episodes, estimated blood loss, and neonatal outcomes (Apgar scores). The diagnostic performance of IJVCI will be evaluated using receiver operating characteristic (ROC) curve analysis.

Inclusion Criteria:

• Age between 18 and 45 years
• ASA physical status II-III
• Diagnosed with preeclampsia
• Scheduled for cesarean delivery under spinal anesthesia with cesarean urgency classified as Lucas category 3-4
• Gestational age ≥28 weeks
• Provided written informed consent

Exclusion Criteria:

• Cesarean urgency classified as Lucas category 1-2
• Gestational age <28 weeks
• ASA physical status ≥ IV
• Known renal disease
• Cardiac instability or known arrhythmia
• Requirement of general anesthesia or sedation
• Inability to provide informed consent

This study includes only female participants because it investigates preeclamptic pregnant women undergoing cesarean delivery under spinal anesthesia, with cesarean urgency classified as Lucas category 3-4. Preeclampsia is a pregnancy-specific condition and therefore occurs only in pregnant women.

Pregnant women diagnosed with preeclampsia who are scheduled for cesarean delivery under spinal anesthesia at Ankara Bilkent City Hospital, with cesarean urgency classified as Lucas category 3-4. Eligible participants are aged 18-45 years, have ASA physical status II-III, and have a gestational age ≥28 weeks. Participants will be evaluated for the development of spinal anesthesia-associated hypotension within the first 20 minutes after spinal anesthesia..